Next Steps... Need help on my 2nd time around

I could really use some help with my algae scrubber.

This is my 2nd time around with my Rain 2 unit. The first time, I slowly ramped up to using 4 lights and was getting incredibly thick green algae growth until one of the tabs on top of my green grabber screen broke off and I had to start over with a new replacement green grabber screen.

The growth since then has always been a brown-ish color which I understand is due to low-nutrients(?).
I feed once a day.

The last time I spoke with you on this, the suggestion was to turn on a 2nd light and stay that way until I started getting growth in the middle of the screen. Three weeks later, there still isn't a lot of growth in the middle.

My lights run from 1pm - 9am ( 20 hours ). I have 2 lights on ( high on one side, low on the other ).
Water flow is good - maybe on the high side if anything.

I’m not able to get any consistent growth in the middle and the type of growth is this brown-ish growth.
I’d like to get to the point where I have all 4 lights working and work towards the more healthy looking green algae that I had before.
I am getting thick green algae growth at the top of my screen.

Questions :
Am I doing something wrong ?
Should I stay with 2 lights for now but increase the light schedule to boost growth?
Why am I getting the brown-ish algae vs green
When should I ramp up and add in my 3rd and 4th light.

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This is actually dark slime growth from high nutrients in the water, and low light, and too long before cleaning; so it looks like the middle of the screen held on as long as it could and let go. Dark slime cannot hold on for too long, on a waterfall design. So do this..

Brush everthing clean (slot, tray too) so you see the white open screen holes.

Plug in all 4 lights for 20 hours.

Clean in 5 days, down into the white screen holes, and definitely not longer than 7 days max.

Thanks... I've plugged in the 4 lights.
I was already at 20 hours lights on ( yeah!)
Normally I clean every 7 days but will reduce to 5 days and see how this develops

Thanks again